What's Whitehall's attitude to software procurement? A cynic might sum it up as "nobody ever got sacked for buying Microsoft".

The current government has vowed to change the civil service mindset that has always preferred to spend money with the biggest firms and has been conservative about open source software.

The Cabinet Office Minister Francis Maude has vowed to create a level playing field for open source as part of a drive to cut costs.

Now a BBC Freedom of Information (FOI) request has given us a glimpse of how big the challenge will be.

We asked government departments for details of how much they had spent on proprietary software over the past year, and how much open source software they had acquired.

The responses have been dribbling in for months now (available as a Google doc or as an Excel spreadsheet), and they've varied from detailed accounts of software and expenditure, to refusals to provide any information on the grounds that it would cost too much.

This is not the kind of FOI request that unveils some shocking secret, but it does provide insights into the kind of software civil servants are buying, and why open-source providers may struggle to get a hearing.

So, for instance, the Home Office provided a detailed list of about £26m worth of proprietary software acquired over 18 months.

Of that, £21m went to just one business, Raytheon Systems for "IT, Broadcasting and Telecoms software".

It seems extraordinary to push something like 80% of your software budget to one provider - but who knows whether an open-source supplier could have provided a product that would have done the job?

The Ministry of Defence was unable to provide a breakdown but says its biggest IT organisation DE&S ISS spent £40.7m on procuring software between February 2009 and March 2011.

Perhaps not a huge budget for such a big organisation but where did the money go?

They do mention a few products - much of it security software like McAfee Anti Virus - but do not say what individual items cost.

In its response the department says that, while it is progressively taking a more centralised approach, "there is no centrally held record of software (proprietary or open source) held across the MOD".

There is also a partial list of some open-source products used, including the Firefox browser - though last time I inquired it seemed you were more likely to find an ancient version of Internet Explorer on a soldier's desktop PC.

By contrast, the Department for Schools did supply quite a lot of detail.

One item that caught my eye was £164,063 on something called Colligo Solution.

This is described as something which will "enhance the interoperability of Microsoft Office 2003 specifically Microsoft Outlook/Exchange 2003, with Microsoft Office SharePoint Server 2007" for all of the department's 3,500 staff.

He is on a Cabinet Office committee advising on how open source might best be promoted in Whitehall, and is not unsympathetic to the efforts of some civil servants to make this happen.

But he points to that Colligo Solution software - needed to upgrade an existing Microsoft program - as an example of the challenges.

"I don't know the exact story with that product but often they've already wasted a lot of money in the wrong place," he says. "They're locked in, and then they need to pay more money to stay where they are."

Uphill struggle

He thinks there is a big cultural problem because, while civil servants know how to deal with big firms like Microsoft and have existing relationships with them, they simply don't know how to start with open source.

"How do you buy something that's free?" he asks. "It's the job of people like me to help them work it out."

Mr Mackintosh also believes that by outsourcing so much of its IT operations, Whitehall has lost the ability to understand what might work.

He says: "They need to be able to take a few more risks, but they don't have the skills internally to assess the software."

I also showed the documents to Bryan Glick who, as editor of Computer Weekly, spends much of his time reporting on government IT policy.

Pointing at the numerous small amounts spent here and there he says: "It shows how little centralised spending control there is and how much duplication."

This, he thought, reinforced what Sir Philip Green said in his purchasing review last year about government missing out on economies of scale.

Bryan was not surprised that many of the government departments could not give us much detail on their software spending.

"Where a large private sector firm would almost certainly have some form of software asset register for audit purposes, there's nothing like that in Whitehall," he explained, "although they're working on just that at the Cabinet Office."

Right now, the idea of trying to work with Whitehall is pretty daunting to small, open-source providers.

The good news is that there is plenty of political weight behind opening the doors to new software ideas - especially if they can save money.